The separation and electrowinning of bismuth from a bismuth glance concentrate using a membrane cell

The main aim of this study was to separate and recover bismuth from a bismuth glance concentrate through leaching, purification and electrowinning from chloride solution. This paper reports on optimization of the process parameters for hydrochloric acid leaching and electrowinning in a membrane cell. Parameters such as bismuth and sodium chloride concentration in catholyte, temperature, current density etc. were examined for their effect on the voltage requirement and current efficiency of bismuth electro-deposition. A maximum current efficiency of > 97% was attained with an catholyte composition of 70 g/L Bi, 25 g/L NaCl, 4.5 mol/L HCl and an anolyte composition of 20 g/L NaOH at 55 °C and a cathode current density of 200 A/m2. Under these optimized conditions, the cathode bismuth purity was 99.98%. An XRD analysis of the condensed salt obtained from the anolyte identified pure sodium chlorate, which can be recycled to the leaching stage.